Subject: Re: How to check for a 50 or 75 ohm connector
Summary: What do you think of these ping times eh?
Reply-To: You can't see me, and I pass right through planets...
X-Newsreader: Forte Agent 1.91/32.564
Date: Sun, 22 Dec 2002 22:29:43 GMT
NNTP-Posting-Date: Sun, 22 Dec 2002 17:29:43 EST
On 22 Dec 2002 21:05:18 GMT, Alun Palmer Gave us:
>The centre pins on 75 Ohm BNC plugs are very slightly larger, so that
>inserting them in a 50 Ohm BNC socket causes damage by enlarging the hole.
>I used to work in a lab where we had both.
>I'm not sure how F connectors got into this thread, but they are nasty
>rubbish, worse even than Belling-Lee connectors. Only use F connectors if
>you absolutely have to. They make UHF connectors look like an engineering
>masterpiece by comparison, which they're not.
Whatever. Your opinions are probably as good as your
mis"information" is. Which is nil. The center pins are the SAME
diameter. The connector you refer to as causing damage is NOT of the
BNC type. In order to be called BNC legally, it has to be able to
plug into a BNC connector jack. Period. And that would be ANY BNC
jack, and that would be without subsequent damage.
>F connectors leak RF in and out like a sieve. One of my old colleagues did
>extensive tests of 'transfer impedance' (this has nothing to do with
>characteristic impedance, but is a measure of screening) and could find
>nothing under the sun that had worse screening than an F connector.
The shield level of the cable used is a determining factor in that
test as well.
Also, the assembler has to know what the hell is going on in order
to fashion the things right as well.